85f2a4320e
Ensure the out value 'uc' in get_ucall() is properly reporting UCALL_NONE if the call fails. The return value will be correctly reported, however, the out parameter 'uc' will not be. Clear the struct to ensure the correct value is being reported in the out parameter. Signed-off-by: Aaron Lewis <aaronlewis@google.com> Reviewed-by: Andrew Jones <drjones@redhat.com> Reviewed-by: Alexander Graf <graf@amazon.com> Message-Id: <20201012194716.3950330-3-aaronlewis@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
116 lines
3.0 KiB
C
116 lines
3.0 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* ucall support. A ucall is a "hypercall to userspace".
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*
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* Copyright (C) 2018, Red Hat, Inc.
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*/
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#include "kvm_util.h"
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#include "../kvm_util_internal.h"
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static vm_vaddr_t *ucall_exit_mmio_addr;
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static bool ucall_mmio_init(struct kvm_vm *vm, vm_paddr_t gpa)
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{
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if (kvm_userspace_memory_region_find(vm, gpa, gpa + 1))
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return false;
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virt_pg_map(vm, gpa, gpa, 0);
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ucall_exit_mmio_addr = (vm_vaddr_t *)gpa;
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sync_global_to_guest(vm, ucall_exit_mmio_addr);
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return true;
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}
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void ucall_init(struct kvm_vm *vm, void *arg)
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{
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vm_paddr_t gpa, start, end, step, offset;
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unsigned int bits;
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bool ret;
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if (arg) {
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gpa = (vm_paddr_t)arg;
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ret = ucall_mmio_init(vm, gpa);
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TEST_ASSERT(ret, "Can't set ucall mmio address to %lx", gpa);
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return;
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}
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/*
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* Find an address within the allowed physical and virtual address
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* spaces, that does _not_ have a KVM memory region associated with
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* it. Identity mapping an address like this allows the guest to
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* access it, but as KVM doesn't know what to do with it, it
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* will assume it's something userspace handles and exit with
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* KVM_EXIT_MMIO. Well, at least that's how it works for AArch64.
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* Here we start with a guess that the addresses around 5/8th
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* of the allowed space are unmapped and then work both down and
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* up from there in 1/16th allowed space sized steps.
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*
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* Note, we need to use VA-bits - 1 when calculating the allowed
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* virtual address space for an identity mapping because the upper
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* half of the virtual address space is the two's complement of the
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* lower and won't match physical addresses.
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*/
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bits = vm->va_bits - 1;
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bits = vm->pa_bits < bits ? vm->pa_bits : bits;
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end = 1ul << bits;
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start = end * 5 / 8;
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step = end / 16;
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for (offset = 0; offset < end - start; offset += step) {
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if (ucall_mmio_init(vm, start - offset))
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return;
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if (ucall_mmio_init(vm, start + offset))
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return;
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}
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TEST_FAIL("Can't find a ucall mmio address");
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}
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void ucall_uninit(struct kvm_vm *vm)
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{
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ucall_exit_mmio_addr = 0;
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sync_global_to_guest(vm, ucall_exit_mmio_addr);
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}
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void ucall(uint64_t cmd, int nargs, ...)
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{
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struct ucall uc = {
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.cmd = cmd,
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};
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va_list va;
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int i;
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nargs = nargs <= UCALL_MAX_ARGS ? nargs : UCALL_MAX_ARGS;
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va_start(va, nargs);
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for (i = 0; i < nargs; ++i)
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uc.args[i] = va_arg(va, uint64_t);
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va_end(va);
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*ucall_exit_mmio_addr = (vm_vaddr_t)&uc;
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}
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uint64_t get_ucall(struct kvm_vm *vm, uint32_t vcpu_id, struct ucall *uc)
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{
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struct kvm_run *run = vcpu_state(vm, vcpu_id);
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struct ucall ucall = {};
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if (uc)
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memset(uc, 0, sizeof(*uc));
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if (run->exit_reason == KVM_EXIT_MMIO &&
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run->mmio.phys_addr == (uint64_t)ucall_exit_mmio_addr) {
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vm_vaddr_t gva;
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TEST_ASSERT(run->mmio.is_write && run->mmio.len == 8,
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"Unexpected ucall exit mmio address access");
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memcpy(&gva, run->mmio.data, sizeof(gva));
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memcpy(&ucall, addr_gva2hva(vm, gva), sizeof(ucall));
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vcpu_run_complete_io(vm, vcpu_id);
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if (uc)
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memcpy(uc, &ucall, sizeof(ucall));
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}
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return ucall.cmd;
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}
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